Pressure die-casting appliance



Nov. 18, 1'930. K. F. WAGNER I PRESSURE DIE CASTING APPLIANCE Filed Feb.

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Inverzn?" Karl Fri ulrich Waynr 3:/ ./Zmrneys v Patented Nov. 18, 1930UNITED STATES PATENT OFFICE KARL FRIEDRICH WAGNER, VI? FEUERBACH, N EARSTUTTGART, GERMANY, ASSIGNOR T0 ELEKTRONMETALL G. M. B. H., OFCANNSTATT-STUTTGART, GERMANY PRESSU'RE DIE-CASTING APPLINCE Applicationfiled February 17,1928, Serial No. 255,093, and in Germany February 19,1927.

This invention relates to a pressure-diecasting a pliance for castingmagnesium and its a loys `and other easily oxidizable metals.

In the attempts hitherto made, to cast magnesium and its high percentagealloys, such as the so-called Elektron metal, in pressure diecastingappliances the apparatus employed for example in connection withaluminum have been found unsuitable. This has been found due in thefirst place to the fact that these appliances do not take into accountthe reat readiness with which magnesium oxidizes. If a large supply ofanalloy of magnesium is kept in a molten state, and freely exposed to theair, the continuous slight oxidation of the magnesium on its surfacecauses the formation of films of oxide which owing to the internalmovement of'the melt, mingle therewith. In course of time not only doesthe metal become thickened but, in addition, the quality of the castingsdeteriorates because the oxide films taken up by the metal lower theinternal cohesion of the' latter and thereby impair the mechanical.strength of the products.

My present invention aims at providing apressure-die-casting appliancewhich overcomes the aforesaid specific diiliculties for magnesiumalloys. To this end, the appliance consists essentially in three l mainparts g (1) The furnace casing through which the combustion gases arepassed, and its cover upon which the pressure-die-casting mould isplaced and which is provided with the auxiliary members such as metalinlet valve and compressed-air valve; l

(2) The melting Crucible whichV is kept quite full through thesuperimposed charging shaft, and .which itself contains (3) The castingvessel which is lilled with more than the amount of metal to be inJectedfor the time being.

In order more clearly to explain the invention, reference is made to theaccompanying diagrammatic drawing which illustrates an embodiment of theinvention constructed in accordance with the principles above. setforth,rand in which Figure 1 is a longitudmal,

'2 a transverse, vertical section taken along line 2 2 of Figure 1.

The iron melting crucible A displays the characteristic feature of aslanting bottom the one end of which merges into a tube which projectsthrough the partially lined furnace casingy B and is there provided witha seal C. This arrangement serves to tap the metal in the event ofstoppages and to remove inipurities, if any.

The characteristic feature in the operation of this Crucible is that inits normal function it is always kept completely filled by means of thecharging shaft D and that normally the meta-l stands sufficiently highin the shaft to exert a hydrostatic pressure on the metal in theCrucible. For this purpose the charging shaft D which is mounted uponthe crucif v In this manner, the molten metal is out of contact with theatmosphere except overa small surface in the charging shaft, so that bythis means, and also by virtue of the fact that this portion of themetal is at a temperature only slightly above the melting point, theopportunity for oxidation is restricted to a minimum. For furtherprotection against the access of air, the lid Dl of the charging shaft Dis arranged to form a receptacle for protective substances, the vapoursof which can escape through" the small openings D2 into the shaft. 'Thepreferred protective substances are those (for example sulfur), Whosevapours-whether in themselves or after oxidation by atmosphericoxygenact as protective gases. In the same manner small amounts of theprotective substances can be introduced into the nozzle shortly beforeplacing the mould in position, by which means the protective gases passinto the mould, partly automatically and partly unthe lower portion F istubular while the flatl upper portion E is provided with a flange bymeans of .Which it is suspended in the top of the Crucible with the aidof sealing fillets and tially cylindrical chamber G for introducing afluid under pressure (compressed air for instance) and a substantiallycylindrical duct connecting the bottom end F1 of said chamber with thenozzle for squirting out the liquid metal, in such a manner that lthewall of the said chamber G turned towards the said duct joins to thelatter with a sharp edge at F1. At this point the circular crosssectionof the duct of the casting vessel preferably turns into a attened,elliptical or semi-circular Cross-section of the same superficial area.

The pressure chamber is essentially circular in cross-section and ispreferably not too small in dimension so that, independently of theamount of metal discharged into the mould P in position for the timebeing, the admitted pressure air cannot, in any Circumstances, penetrateas far as the point F1. In close proximity to this point is the valve Hfor admittinggmetal into the casting vessel. On opening said valve themetal passes from the melting Crucible into the casting vessel andintothe pressure chamber (the pressure having been released) and into thenozzle duct and mounts therein up to the level of the metal in thecharging shaft; that is to say until a short distance below the mouth ofthe noz'zle.

The upper cover of the appliance is formed by a plate K which is asingle Casting with a vaulted top L. The plate is provided with anaperture corresponding to the Circumference of the Crucible so that theCrucible A can be inserted into the plate K and lies on the edge K1thereof. The vault is provided with a corresponding aperture which iscovered at L1 by a superimposed additional lid M through which themembers controlling the appliance pass, and which is Covered in placesby heat-insulating plates B. By means o f the hollow space between thefurnace plate and vault, the heat-ing gases which enter into the bottomof the furnace Casing at O, can be passed through the hollow furnacecasing in such manner that, not-only is the melting Crucible A heated,but `also the upper side of the casting vessel, surrounding the seatingof the nozzle J, the upper part of the metal inlet valve H, the pressurechamber G, and the charging shaft D of the crucible in the proximity ofwhich the heating gases pass out of the Casing. In other respects themachine is operated in the same manner as-the usual machines.

Although, according to the foregoing the 'Casting appliance is primarilyintended to be applied to magnesium and its alloys, it proves to beuseful too in the employment for other easily oxidizable metals oralloys. I claim: '1. In a pressure die-casting apparatus a melting andcharging device comprising, in combination, a Closed Crucible serving asa 'metal container, a feeding shaft extending melting and chargingdevice comprising, in

combination, a Closed Crucible serving as a metal container, a furnacecasing surrounding said Crucible and provided with a detachable cover,said Crucible being suspended by said Cover, a feeding shaft extendingupwards from said Crucible, a substantially U- shaped Casting vesselsuspended by and within said Crucible, means for introducing underpressure a fluid into one end of said casting vessel a nozzle fordischarging molten metal from the opposite end of said Casting vessel,the feeding shaft, fluid inlet and discharging nozzle passing throughsaid cover of said furnace Casing, and a valve connecting the interiorof said casting vessel with the interior of said Crucible.

3. In a pressure die-casting apparatus a melting and charging deviceComprising, in combination, a closed Crucible consisting of a pot and adetachable cover and serving as a metal container, a furnace Casingsurrounding said Crucible and provided with a hollow detachable cover,said Crucible being suspended by the cover of said furnace casing, ductsfor passing the heating gases from the furnace Casing into the interiorof. said furnace casing cover, a feeding shaft extending upwards fromsaid Crucible, a substantially U-shaped Casting vessel, both ends ofsaid casting vessel being passed through the cover of said Crucible andrigidly connected therewith in a gas-tight manner, and means forrendering gas-tight the contacting rims of said Crucible cover and saidCrucible pot.

4. In a pressure die-casting apparatus, in combination, a closedCrucible serving as a metal Container, a feeding shaft extending upwardsfrom said Crucible, a lid covering the opening of said shaft and aperforated receptacle attached tothe bottom of said lid.

5. In an pressure die-Casting apparatus comprising a metal Container anda casting vesselwithinsaid container, a castin vessel Comprising asubstantially straight C amber Connected at one end with a pressureinlet, a

duct connecting the other end of the chamber with a discharging nozzle,said duct issuing from said chamber at a denitean le, and a valve in theproximity of said cham er connecting said duct with the interior of themetal container. Y

6. In a pressure die-casting apparatus comprising a metal container anda casting vessel within said container, a casting vessel comprising asubstantially straight chamber connected at one end with a pressureinlet, a

duct connecting the other end of the chamber with a discharging nozzle,said duct issuingfrom said chamber at a definite angle, and a Valveconnecting said duct with ythe interior of the metal container in thelproximity of said chamber actuated by a stem in a directionsubstantially parallel to said-chamber.

v''. In 4' a pressure die-casting apparatus comprising a metal containerand a casting vessel Within said container, a casting vessel comprisinga substantially straight chamber connected at one end with a pressureinlet, a duct connecting the other end of the chamber with a dischargingnozzle, said duct issuing from said chamber at a definite angle, thecross'section of said duct being narrowed in the proximity of its pointof issue from the end of said chamber Wthoutbeing materially reduced inarea and a valve connecting said duct with the interior of the metalcontainer in the proximity of said chamber, actuated by a stem in adirection parallel to said chamber.

'In testimony whereof I have hereunto t my hand.

KARL FRIEDRICH WAGNER.

